After harvest grain such as, for example, wheat, rye, barley, canola, soybeans, is stored in storage bins, either on site at a farm or in large commercial storage facilities, prior distribution for processing or sale. Typically, the grain is stored in the storage bins during fall and winter.
Temperature changes due to changing seasons result in an unequal temperature distribution within the grain stored inside the storage bin causing natural convection of air through the grain and causing moisture to migrate therewith. The moisture then gathers in the top portion of the stored grain causing it to spoil. Depending on the temperature and the moisture content of the grain spoilage occurs within weeks or even days.
To prevent spoilage of grain stored in storage bins grain aeration systems or grain drying systems are employed. In grain aeration systems typically a fan provides a flow of outside air into and through the stored grain. Unfortunately, aeration systems are relatively complex and expensive to manufacture, install, and operate. Furthermore, in conditions of high humidity of the outside air the aeration is ineffective in preventing spoilage of the grain. Grain drying systems are more effective in humid conditions of the outside air, but are even more expensive to operate than aeration systems and care must be taken that the stored grain is not damaged due to too high temperatures of the heated air provided by the grain drying system.
Some systems use a fan to generate an air flow and others use natural convection to effect the movement of the air. In some cases the air moves inwardly from the wall to a center discharge duct and in other cases the air flow moves outwardly from a center duct to the wall.
One problem of systems of this type is that of allowing air to flow either inwardly or outwardly at the bin wall. Perforations through the wall must prevent prevents penetration of water and escape of the grain.